Ruthenium catalysts have been known for many years to be the most active of the Group VIII metals in the carbon monoxide/hydrogen synthesis reaction. At low temperatures and very high pressures ruthenium can produce high molecular weight paraffinic waxes. At about atmospheric pressure methane is the principle product. Because it is such a good hydrogenation catalyst, ruthenium, until recently, has not been noted for its capacity to produce olefins.
U.S. Pat. No. 2,250,421 discloses a method for preparing liquid hydrocarbons from synthesis gas mixtures in which a metal carbonyl is decomposed at high temperatures in an inert hydrocarbon oil to yield finely divided metal forming a colloidal suspension. It is also taught that the metal carbonyl can be decomposed in the presence of a solid promoter and no inert hydrocarbon oil to directly deposit on the promoter. Mentioned as suitable metal carbonyls are the carbonyl compounds of iron, cobalt, chromium, molybdenum, tungsten, and ruthenium. Suggested promoting agents are alumina, thoria, ceria, manganese oxide, combinations thereof, and the like.
U.S. Pat. No. 2,623,058 discloses a process for preparing liquid hydrocarbons from carbon monoxide and hydrogen using a catalyst prepared by reacting an active metal of Groups VI or VIII of the Periodic Table with carbon monoxide to form a volatile carbonyl compound and decomposing the carbonyl compound on an essentially inactive readily fluidizable carrier material which may be a substance containing silica, alumina or magnesia in various combinations. A promoter such as the oxides of chromium, zinc, aluminum, magnesium, manganese and the rare earth metals may be incorporated into the carrier material.
U.S. Pat. No. 4,042,614 discloses a method for synthesizing C.sub.2 -C.sub.10 olefinic hydrocarbons with reduced wax formation using a catalyst comprising ruthenium on titanium dioxide. Suitable ruthenium salts such as ruthenium chloride, ruthenium nitrate or ruthenium acetate may be used in preparing the ruthenium catalyst.
U.S. Pat. No. 4,171,320 discloses a method for the synthesis of hydrocarbons with reduced methane formation and for the selective production of C.sub.2 -C.sub.5 olefinic hydrocarbons using as a catalyst ruthenium on a support comprising a Group VB metal oxide. As in the previous patent any suitable ruthenium salt may be used in preparing the catalyst.
U.S. Pat. No. 4,199,522 discloses the preparation of C.sub.2 -C.sub.4 olefins by contacting carbon monoxide and hydrogen with a catalyst consisting essentially of at least one material selected from the group consisting of the sulfide, oxide or metal of molybdenum, tungsten, rhenium, ruthenium, nickel, palladium, rhodium, osmium, iridium and platinum and at least one material selected from the group consisting of the hydroxide, oxide or salt of an alkali metal, an alkaline earth metal or thorium.
U.S. Pat. No. 4,206,134 discloses a method for the selective synthesis of low molecular weight olefins using as a catalyst ruthenium on a manganese oxide support. Again, any suitable ruthenium salt may be used in the preparation of the catalyst.
Other patents which teach the selective synthesis of olefinic hydrocarbons by reacting carbon monoxide and hydrogen in the presence of a catalyst include U.S. Pat. Nos. 4,116,994; 4,261,864; 4,261,865 and Canadian Pat. Nos. 1,050,051 and 1,053,266.
U.S. Pat. No. 4,239,499 teaches producing a fuel gas containing a high proportion of methane by passing methanol over a metal catalyst such as ruthenium on alumina which may be stabilized by ceria or thoria.